Translate this page

INSIDE

HEAR THIS PAGE

The Parasite in the Playground

Strays may shed eggs of Toxocara worms, contaminating parks and infecting children. Photo Credit: Gregg Vigliotti for The New York Times

Those stray dogs and cats you see in playgrounds are leaving something behind. They leave roundworms. The technical name for roundworms is Toxocara.

Microscopic eggs from Toxocara are in the feces of animals. They contaminate yards, playgrounds, and sandboxes.Toxocara particles do infect. They cling to the hands of children playing outside. Children bring their hands to their mouths, eyes, and nose. Once inside the body, the eggs soon hatch. Hatching releases larvae that wriggle through the body. Evidence suggests they may even reach the brain. It could compromise learning and cognition.

The government says that about 5 percent of the U.S. has the parasite. That comes to 16 million people.

But who gets the parasite? Most often it is the poor and minorities. The rate among black Americans is almost 7 percent. The infection rate is 10 percent for people living in poverty.

Experts call Toxocara one of the most common parasites in the country. There are few studies about it.

What does the parasite do? Experts link it to lower intelligence and epilepsy. A doctor said we need studies of kids who are poor and not doing well in school.

Most pets with owners who care for them do not carry the parasite. Lower-income areas have more strays.

Experts looked at 21 parks in New York City. They found Toxocara eggs in nine of the parks. Samples from the Bronx were more likely to contain eggs in the larval stage. The larval stage is the more infectious stage. No parks in Manhattan had Toxocara eggs with larvae.Adult Toxocara roundworms live in the small intestines of infected cats and dogs. The eggs are excreted in their feces. Credit Eye of Science/Science SourceLarvae from Toxocara can enter the eyes and cause blindness. They can also infect the liver and lungs.

Adult Toxocara roundworms live in the small intestines of infected cats and dogs. Credit Eye of Science/Science Source

Signs of infection tend to be hard to spot. It can be a slight fever, fatigue, abdominal pain, and cough. These are common symptoms of many illnesses. Few pediatricians think to test for Toxocara.

The infection may clear on its own after months or even years. A doctor said, “But we don’t even know that for sure.”

Doctors treat the infection with the anti-parasitic drug albendazole. Most pediatricians know little about Toxocara.

And that is the problem. It may be the cause of some mental illness. A doctor said, “We know that larvae go to the brain in humans.” But beyond that fact, “we know very little.”

Impairments from Toxocara do not seem to be severe. An expert said that is why it gets little attention.

He said, “It is hard for people to accept that it could be having the effect that it is. We do not know much about its impact. These are larvae burrowing through the brain. It is not something that any mother or father of a child would welcome.”